In die transfer apparatus

ABSTRACT

A mechanism for forming thin metallic skin enclosures from blanks. The apparatus includes a forming assembly including a plurality of die stations. The stations are stepped farther away from an axis along which blanks being processed are positioned at a plurality of die stations. Grippers spaced from each other along the axis and away from the axis at distances substantially the same as die stations are carried by the transfer assembly. A pneumatic actuator can be used to move the transfer assembly reciprocally in directions generally parallel to the axis between first and second axial positions. In the first position the grippers are registered with corresponding die stations. In a second position the grippers are registered with die stations adjacent the ones with which they are registered when the transfer assembly is in its first position. A ram is provided to move the transfer assembly between first and second stepped positions relative to the axis.

TECHNICAL FIELD

The present invention deals broadly with the field of tool and die technology. More narrowly, however, it deals with the forming of multiple, thin metallic skin enclosures from blanks. Even more narrowly, it deals with forming cases defined by a thin metallic skin. A specific focus of the invention is an apparatus and method for forming battery casings by progressively stamping a plurality of blanks at sequenced die stations.

BACKGROUND OF THE INVENTION

Various machines are known in the prior art for progressively forming blanks by passing them through sequential die stations until they conform to a desired size and shape. Successive draws take an initially flat blank of metal and deform it in such a manner so as to prevent wrinkles and cracks from forming in the blank. This is true even though its shape is changed to one that is intended depending upon the particular application to which the work piece is to be put. The ultimate application may be a medical enclosure for a defibrillator or a pacemaker.

Prior art structures employ tools for each individual draw. In some instances, the case needs to be washed and annealed in order to maintain a sufficient degree of pliability for the next successive draw. The time element can be critical in going from draw to draw. Depending upon the number of draws necessary and the treatment between draws, it can take several weeks to complete a particular work piece.

The specific process typically utilized in the prior art passes parts in what is known as a common pass line. In such a methodology, all the presses are in the same horizontal plane. All the tooling has to be in that horizontal plane, and the work pieces are inserted into the draw tool and extracted from the draw tool from the same surface. Such methodology substantially effects drawing the work piece twice because the metal passes twice over the surfaces that actually effect deformation. Such a process can reduce quality by deforming the work piece to push back out a tool. By doing so, a geometry change can occur.

As was previously discussed, time can be an important factor. In one application of such a methodology, a period of time of 45 minutes between draws can be excessive. There is a natural tendency to allow a quantity of work pieces to build up at one machine before they are passed to the next machine. Similarly, because of break time and shift changes, parts may sit unattended for in excess of 45 minutes.

It is to these dictates and shortcomings of the prior art that the present invention is directed. It includes apparatus and methods for sequentially forming a plurality of thin metallic skin structures which solve problems in the prior art.

SUMMARY OF THE INVENTION

The present invention focuses upon both apparatus and methods. It includes apparatus for forming a plurality of enclosures having thin metallic walls. Such enclosures are formed by sequencing a plurality of blanks through progressive die stations. The apparatus includes a forming assembly which has a plurality of die stations spaced along an axis. The stations are stepped serially farther away from the axis in a direction perpendicular to the direction of movement of the blanks along the axis. The stations serve to progressively form the blanks as they are sequentially transferred in the direction of movement along the axis and from one station to another. A transfer assembly mounts a plurality of gripping means for gripping the blanks to transfer them from one station to the next. Such gripping means are spaced from each other along the axis and are serially stepped away from the axis at distances substantially the same as are the die stations. Actuator means to effect movement of the transfer assembly reciprocally in directions generally parallel to the axis are provided. The actuator means move the transfer assembly between a first axial position, in which the gripping means are registered with corresponding die stations, and a second axial position, in which each gripping means is registered with a die station adjacent the station with which it is registered when the transfer assembly is in its first position, advanced in a direction of movement from the first position. Also provided is a ram which moves the transfer assembly between a first stepped position in which the gripping means are withdrawn from the die stations, and a second stepped position, in which the gripping means engage blanks at the die stations.

The actuator means by which the transfer assembly is moved between its first and second axial positions can be pneumatic in nature. By employing a system so constructed, the transfer assembly can be efficiently moved between its first and second axial positions.

Similarly, pneumatic means can be provided to operate the ram in moving the transfer assembly between the first stepped position and the second stepped position. Again, it has been found that such a ram can be optimally operated to accomplish its intended goals.

The present invention is thus an improved apparatus and method for forming multiple metallic enclosures from blanks. More specific features and advantages obtained in view of those features will become apparent with reference to the appended DETAILED DESCRIPTION OF THE INVENTION, appended claims and accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a work piece after a first draw at a die station;

FIG. 2 is a perspective view of a work piece after a second draw at a die station;

FIG. 3 is a perspective view of a work piece after a third draw at a die station;

FIG. 4 is a perspective view of a work piece after a fourth and final draw at a die station;

FIG. 5 is a simplified side elevational view of an apparatus in accordance with the present invention with a transfer assembly in its first axial position and its first stepped position;

FIG. 6 is a view similar to FIG. 5 but in more detail;

FIG. 7 is an enlarged view illustrating a die station;

FIG. 8 is a view similar to FIG. 6 with the transfer assembly in a first axial position and a second stepped position;

FIG. 9 is a view similar to FIG. 8 but with a ram retracting the transfer assembly back toward its first stepped position;

FIG. 10 is a top plan view illustrating a set of grippers gripping a work piece;

FIG. 11 is a view similar to FIG. 10 showing the set of grippers releasing the work piece; and

FIG. 12 is a view similar to FIG. 6 with the transfer assembly in its second axial position and its first stepped position.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawing figures wherein like reference numerals denote like elements throughout the several views, FIGS. 6, 8-9 and 12 illustrate an apparatus in accordance with the present invention. FIG. 5 is a simplified illustration of the apparatus of FIGS. 6, 8-9 and 12. Initial discussion is made with reference to FIG. 5. That figure illustrates a base which mounts a forming assembly. The assembly is elongated along an axis. The axis extends in a direction of movement of work pieces through a plurality of die stations spaced along the axis of the base.

Each die station mounts a tool which, when work pieces are successively processed through from station to station, the shape of a work piece will be progressively more conformed to an intended shape and size. As seen in FIG. 5, the tools, moving in a right-to-left direction in that figure, are successively smaller in cross-section.

FIGS. 1-4 illustrate the size and shape of a blank as it proceeds in a direction of the axis from station to station. The work piece being formed, as illustrated by FIGS. 1-4, is a casing for use in an implantable medical device. While the figures do not illustrate the specific shape of tools to achieve the shape and size of the work piece illustrated in FIGS. 1-4, it will be understood that any shaped sequentially processing tools to achieve a particular constructed work piece can be utilized. It should also be understood, of course, that a die, cooperating with a particular tool, would also be utilized in the forming process.

FIG. 5 illustrates a stepping of sequenced stations wherein they are defined serially farther away from the axis in a direction generally perpendicular to the direction of movement of the work pieces along the axis. Such stepping is for a purpose as will be discussed hereinafter.

The figures also illustrate a transfer assembly which mounts a pair of gripping fingers and a die structure corresponding to a tool at a die station. It is the cooperation of the tool and its corresponding die which effects processing of a work piece at a particular station. As will be seen in the figures, the gripping means/die structure corresponding to a particular die station are stepped from an adjacent station in an amount similar to the distance at which the die stations are stepped from the axis.

The gripping means/die structures are positioned on a platen. The platen is carried by a series of telescoping mounts which allow for the transfer assembly to move from a position wherein the gripping means/die is withdrawn from engagement of the corresponding tool, to another position wherein the gripping means/die engage a corresponding tool to effect sequential formation of the work pieces. A ram is provided to mount the transfer assembly for movement between the first, withdrawn position, and the second, extended position.

As will be apparent, the die structures are ganged. That is, they are fixed with respect to each other in a defined spatial relationship.

The transfer assembly is also mounted for movement in a direction along the axis. Movement is between a first position and a second position. When the transfer assembly is in its first position, the various gripping means/die assemblies are substantially registered with their corresponding tools at the die stations. When the transfer assembly is in its second axial position, the gripping means/die assemblies are generally registered with a die station and its corresponding tool spaced one station to the left (as viewed in FIG. 5). This second axial position of the transfer assembly is illustrated in FIG. 12.

It will be understood that actuator means for moving the transfer assembly reciprocally in an axial direction between its first and second positions, and movement of the transfer assembly by the ram in a direction generally perpendicular to axial movement can be accomplished by an actuator of any appropriate means. It has been found that a pneumatic actuation means is appropriate.

In operation, an initially structured work piece, as illustrated in FIG. 6, is placed over the tool at the first station. Such positioning of the work piece can be accomplished either manually or by employment of a mechanical transfer structure (not shown). The transfer assembly is initially in its first positions both axially and in a direction stepped perpendicular to axial movement. The first movement of the transfer assembly is accomplished by actuating the ram to move the transfer assembly from its first stepped position to the second stepped position. This movement will cause forming to be brought to bear upon the work piece in the first station (that is, in the right-most station as viewed in the figures).

When this forming process is completed, the ram withdraws the transfer assembly to the first stepped position. As withdrawal of the ram proceeds, a stripper, shown in FIG. 7, will facilitate removal of the work piece from the tool, and a pair of fingers of gripping means will grasp the work piece to hold it as the transfer assembly is cycled.

When the transfer assembly is withdrawn to its first stepped position, actuation means then function to move the assembly in an axial direction to a location wherein the gripping means holding the work piece becomes substantially registered with the second die station. Such a station is the one immediately adjacent the first station at which processing has already occurred. With the transfer assembly in this position, another pre-processed blank is placed over the tool in the first station. The ram then moves the transfer assembly, after the fingers having released the first work piece at the second die station, back to its first stepped position. As will be able to be seen, two stations now hold sequentially-processed work pieces over their respective tools. The ram then moves the corresponding dies in a downward direction to process the work pieces in the first and second stations. Subsequent insertion of a pre-processed work piece at Station 1 as previously processed blanks have moved on to subsequent stations will allow for sequential processing of the work pieces in third and fourth stations.

It will be understood that, while four stations are shown in the various figures, a number greater or smaller than four is within the contemplation of the invention. Circumstances might, in fact, dictate six or more stations for processing.

FIGS. 10 and 11 illustrate, in plan, the functioning of gasping fingers. FIG. 10 illustrates the fingers closed onto the work piece with which the fingers are cooperating. FIG. 11 shows the fingers in their release mode. Actuation of the fingers is, of course, coordinated with the positioning of the transfer assembly. Opening and closing of the fingers can be accomplished by mechanical means, a pneumatic system, etc.

It will be understood that this disclosure, in many respects, is only illustrative. Changes may be made in details, particularly in matters of shape, size, material, and arrangement of parts without exceeding the scope of the invention. Accordingly, the scope of the invention is as defined in the language of the appended claims. 

1. Apparatus for forming multiple, thin metallic skin enclosures from blanks, comprising: (a) a forming assembly including a plurality of die stations spaced along an axis, said stations stepped serially farther away from said axis in a direction generally normal to a direction of movement along said axis, said stations for progressively forming the blanks as they are sequentially transferred in a direction of movement along said axis from one station to another; (b) a transfer assembly mounting a plurality of means for gripping the blanks, said gripping means spaced from each other along said axis and serially stepped away from said axis at distances substantially the same as said die stations; (c) actuator means for moving said transfer assembly reciprocally in directions generally parallel to said axis between a first axial position, in which said gripping means are registered with corresponding die stations, and a second axial position, in which each gripping means is registered with a die station adjacent the die station with which it is registered when said transfer assembly is in said first position but advanced in a direction of movement from said first position; and (d) a ram for moving said transfer assembly between a first stepped position, in which said gripping means are withdrawn from said die stations, and a second stepped position, in which said gripping means can engage blanks at said die stations.
 2. Apparatus in accordance with claim 1 wherein said means for gripping comprises a pair of fingers movable between grasping and release positions.
 3. Apparatus in accordance with claim 1 wherein said actuator means is pneumatically operated.
 4. A method of forming thin metallic wall enclosures from blanks, comprising the steps of: (a) positioning a transfer assembly in a first axial position wherein each of a plurality of gripping means are registered with a corresponding die station, and a first stepped position wherein said gripping means are laterally withdrawn from the die stations; (b) placing a blank in a first die station; (c) moving said transfer assembly to a second stepped position wherein a ram effects drawing of said blank in said die station; (d) grasping said die by said gripping means and withdrawing said transfer assembly to said first stepped position; (e) moving said transfer assembly to a second axial position wherein said gripping means are registered with die stations adjacent the stations with which the gripping means are registered when said transfer assembly is in said first axial position; and (f) moving said transfer assembly from said first stepped position to said second stepped position to draw said blank an additional amount. 